The present invention relates to an adhesive aid and to a method for adhering components. In particular, the invention relates to an adhesive aid for the adhering of planar components, at least one component having an opening.
When joining components by adhesion, particularly planar components, it is problematic that, during the joining of the components, if one of the components has openings, such as holes, bores, cutouts, punch holes, etc., adhesive may swell out into the openings and, through these openings, may swell out by way of a component surface. As a result, pre-machining and finishing may be made more difficult or additionally required, such as, for example, a removal of excess adhesive, an exposing of the joint, a metering of the adhesive quantity, a marking of the joining location, etc.
It is an object of the present invention to provide a method and adhesive aid for adhesively joining components, of which at least one has an opening, while at least partially avoiding the disadvantages of the prior art. In particular, it is an object of the present invention to avoid adhesive flow out into openings of components, when joining by adhesion. It is a further object of the present invention to avoid or at least reduce pre-machining and finishing when joining by adhesion.
The above-mentioned object is achieved at least with respect to partial aspects by an adhesive aid and by a method according to embodiments of the invention. In this case, characteristics and details which are described in connection with the adhesive aid, also apply to the method as well as, in each case, vice-versa and reciprocally, so that, with respect to the disclosure, reference is made or can always be made reciprocally to the individual aspects of the invention.
According to one aspect of the present invention, an adhesive aid is provided for use during the adhesive joining of a first component with a second component by way of an adhesive situated in an adhesive gap between respective adhesive surfaces of the components. At least the first component has an opening which opens into its adhesive surface. The adhesive aid has an insert section designed to be inserted into the opening and having an outer insert outer contour, which correlates with the inner contour of the opening. The adhesive aid has a displacement section, which adjoins the insert section for the displacement of adhesive into the adhesive gap. The displacement section has a protrusion in the radial direction opposite the insert outer contour, which has and having a flexible, particularly an elastic design.
Here, an adhesive aid is an auxiliary device which is used for the purpose of joining by adhesion but not for remaining in the finished components joined by adhesion. For the purpose of the invention, any part of a spatial structure may be a component, irrespective of whether it is a half-finished product, a semi-finished product, a joining element, an individual layer of a laminate or the like. The adhesive aid according to the invention can particularly suitably be used for the adhesive joining of layers of a composite fiber component, such as CFRP or GFRP layers, or of components made of a composite fiber material, such as CFRP or GFRP, but can also be used for other materials, such as metal, synthetic material or wood. CFRP is a plastic material reinforced by fibers (long fibers or short fibers), generally called carbon-fiber-reinforced plastic.
For the purpose of the invention, an opening extends between two opposite sides of a component. The opening may be a bore, a punch hole or a gap and may basically have any shape. Since the insert outer contour correlates with an inner contour of the opening, the insert outer contour rests at least in sections against the inner contour of the opening such that a secure fit of the adhesive aid is ensured in the opening if the adhesive aid is used for the intended purpose. This can be achieved in that, in its cross-section, the insert outer contour corresponds to the inner contour of the opening, as required, with a certain oversize. A direction of the dimension of the opening is an axial direction and a plane transversely to the dimension direction of the opening is the cross-sectional plane. Correspondingly, a direction transversely to the axial direction (dimensional direction of the opening) is the radial direction. With respect to the opening, the thus defined directions coincide with the direction definitions with respect to the adhesive aid if the latter is used as intended.
In the axial direction, the insert outer contour may extend over the entire thickness (depth) of the first component, thus over the entire “length” of the opening, but may also be longer or shorter.
Viewed in the circumferential direction, it may also be advantageous for a continuous sealing to occur over the circumference, between the insert outer contour and the inner contour of the opening. However, for complying with a correlation, it is sufficient for the insert outer contour to be supported only at points or sections at the opening, which may take place, for example, in the case of a longitudinal ribbing of the insert section. In this case, the outermost contour sections of the insert outer contour, which can be understood to be supporting sections, define a correlation contour, which corresponds to the inner contour of the opening in the circumferential direction. In the event of an opening with a circular cross-section, which exists, for example, in the case of a bore, the correlation contour, for example, a surrounding area, in the case of an opening with an arbitrary cross-section would, for example, be a so-called “surrounding contour”, which is generated, for example, by radially outermost sections of the insert outer contour. For this purpose, a protrusion opposite the insert outer contour is a protrusion opposite the correlation contour. This means that, in the radial direction, the protrusion also always protrudes to the outside beyond the inner contour of the opening, and therefore particularly also to the outside beyond the gap-side edge of the opening. As a result of the protrusion of the displacement section, the latter has a greater dimension in the cross-sectional direction (radial direction) than the insert section, particularly than the insert outer contour, and thereby also a greater dimension than the opening. The displacement section therefore takes up a space in the adhesive gap that projects in the radial direction from the edge of the opening into the adhesive gap. As a result, adhesive is also pressed away from the opening in the radial direction into the adhesive gap, or a penetrating of adhesive into the space taken up by the displacement section is prevented, whereby the edges of the opening remain reliably free of adhesive, even if the adhesive had already been applied beforehand. On the whole, the adhesive aid acts as a blockage to the adhesive; i.e. the inner contour of the opening and the outer edge of the opening remain free of adhesive. In this case, it is advantageous for the used adhesive to be of comparatively low viscosity. It is understood that the correlation of the insert outer contour with the inner contour of the opening in the axial direction has to be present at least within the opening, but is not required over the entire axial length of the opening or an axial component thickness of the first component.
As a result of the flexible formation of the displacement section, the protrusion can be compressed or deformed by the opening during the removal of the adhesive aid, so that the adhesive aid can by pulled out of the opening without damaging the edges of the component and without tearing off the protrusion. The flexible formation of the displacement section can be implemented, for example, by a flexible material, such as an elastomer or by constructive devices, such as a double-wedge arrangement or an inflatable design. Particularly, the elastic formation can also be limited to the protrusion itself or may be particularly pronounced there. It is currently preferred for the entire adhesive aid to be made of an elastomer in one piece.
The precise implementation of the protrusion will be carried out by a person skilled in the art on the basis of the dimensions and other characteristics of the components. The dimension of the protrusion and the flexibility in the area of the protrusion are preferably adapted to material characteristics of the first component in the area of the opening and to adhering characteristics of the adhesive on the components such that the adhesive aid can be removed from the opening so that edges of the opening will at least essentially remain without damage and an adhesive joining between the components remains at least essentially undamaged.
In a preferred embodiment of the adhesive aid according to the invention, a length of the displacement section is adapted to a specified thickness of the adhesive gap. In this case, the length is measured in the axial direction. The specified thickness of the adhesion gap may, for example, be determined by the characteristics of the adhesive to be used, the dimensions and the structure of the components to be joined by adhesion, as well as other parameters. During the joining of CFRP components by adhesion, the adhesive gap may have a thickness of, for example, approximately 0.1 to 0.6 mm; depending on the manner of application, adhesive gap thicknesses of up to 5 mm are also contemplated. When the length of the displacement section is equal to or greater than the specified thickness of the adhesive gap, a limit stop for a contact pressure path during a joining by adhesion is formed by the protrusion which, during joining by adhesion, is squeezed between the components, in which case, the flexibility of the protrusion can also be utilized. This is also useful for process reliability when joining by adhesion. In addition, a space that is reliably free of adhesive is also formed between the adhesive surfaces because the displacement section will then fill the adhesive gap along the entire axial length.
In a further embodiment of the adhesive aid according to the invention, the displacement section forms an axial end of the adhesive aid. In other words, the displacement section particularly has a plane face which forms an axial end of the adhesive aid. In this embodiment of the adhesive aid, adhesive connections can advantageously be established, where only the first component has an opening. When, as described above, the displacement section is at least as long as the adhesive gap is thick, the surface of the second component situated opposite the opening will also remain free of adhesive because the face of the displacement section contacts the adhesive surface of the second component and will displace the adhesive from there.
In another embodiment of the adhesive aid according to the invention, the displacement section is adjoined by a second insert section in the axial direction. In this case, the second insert section is adapted like the first insert section in a second insert outer contour to an inner contour of an opening of the second component. As a result, connections formed by adhesion, in which also the second component has an opening which, in particular, is coaxial with the opening of the first component, can be advantageously established. In this case, a penetration of adhesive also into the opening of the second component can be prevented. The adhesive aid may also have two or more displacement sections, which are each separated from one another by an insert section. This means that also more than two components can be joined by adhesion with the above-mentioned advantages.
In a further development of the adhesive aid according to the invention, the adhesive aid has a placing section adjoining the insert section and having a placing surface for a placing onto a free surface, which faces away from the adhesive surface of the first component, around the opening, preferably a length of the insert section corresponding to a thickness of the first component in the area of the opening. As a result, a process-reliable limit stop is created for the inserting of the adhesive aid into the opening, and a pressing-on of the components during the joining by adhesion can at least be partially provided also by means of the adhesive aid. Light-weight components can also be held by the adhesive aid and can be guided to the second component. This may also facilitate handling and save process steps.
In a further embodiment of the adhesive aid according to the invention, the adhesive aid has a handling section which is designed for handling the adhesive aid. In particular, the handling section is designed to adjoin the insert section or is designed together with this insert section but is definitely situated on a side of the adhesive aid facing away from the displacement section. The handling section may, for example, be attached, for example, in the shape of a shaft, by which the adhesive aid can be manually gripped. On the other hand, the handling section may also be integrated, as, for example, in the shape of an internal thread or blind hole placed in the side facing away from the displacement section or in the face of the insert section, which can permit, for example, the mounting of a tool holding fixture or the coupling with a robot arm or the like.
In a preferred embodiment of the adhesive aid according to the invention, the adhesive aid is produced completely of an elastic material, particularly a silicone or an elastomeric plastic. A completely elastic design of the adhesive aid is advantageous with respect to the process and is particularly easily produced. In particular, the adhesive aid has a one-piece design, i.e. is made from one mold. Silicone is easily and cost-effectively available as the elastic material; it has good sliding characteristics and adheres poorly to most other materials once it has been cross-linked. Instead of silicone, a different material, such as elastomeric plastics, can also be used, particularly a material adapted to the adhesive to be used. As an alternative, the use of an elastic material may be limited to defined areas, for example, the protrusion at the displacement section or the displacement section as a whole, an area of the insert section resting against the opening, or other areas.
In a further development of the adhesive aid according to the invention, the insert section has an undercut at the end adjoining the displacement section. In other words, viewed in the axial direction, the undercut is arranged between the protrusion and the insert outer contour. The undercut facilitates the handling of the adhesive aid because, when the adhesive aid is inserted, the protrusion is accommodated by the undercut and, when the adhesive aid is removed, the bending point of the protrusion is displaced radially inward. Damage to and tearing-off of the protrusion can thereby be even more easily avoided.
In a second aspect, the present invention also relates to a method of joining by adhesion a first component with a second component, at least the first component having an opening which opens into its adhesive surface. According to the invention, the method has the steps of:
a) placing the above-described adhesive aid in the opening of the first component;
b) applying a flowable adhesive to the adhesive surface of the first component and/or the adhesive surface of the second component;
c) bringing the first component and the second component onto one another with mutually facing adhesive surfaces, and preferably exerting a predefined adhesion pressure upon the first and the second component; and
d) removing the adhesive aid from the opening.
For the intended use, the placing of the adhesive aid takes place such that the insert section is inserted into the opening of the first component, the displacement section of the adhesive aid projecting from the opening in the inserting direction. Preferably, the component that is provided with adhesive is the one which does not have the adhesive aid or the opening or is free of those. As a result of the use of an adhesive aid according to the invention, a method according to the invention has the same advantages as described with respect to the adhesive aid itself.
The method according to the invention is preferably implemented such that the inserting of the adhesive aid and the removal of the adhesive aid are carried out from the side of the first component facing away from the adhesive gap. This means that no opening for removing the adhesive aid has to be present in the second component, and the side of the second component facing away from the adhesive gap, in other words, the backside of the adhesive connection, does not even have to be accessible.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.